Teréz Nagy

Acatalasemia and diabetes mellitus

The enzyme catalase catalyzes the breakdown of hydrogen peroxide into oxygen and water. It is the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide is a highly reactive small molecule formed as a natural byproducts of energy metabolism. Excessive concentrations may cause significant damages to protein, DNA, RNA and lipids. Low levels in muscle cells, facilitate insulin signaling. Acatalasemia is a result of the homozygous mutations in the catalase gene, has a worldwide distribution with 12 known mutations. Increased hydrogen peroxide, due to catalase deficiency, plays a role in the pathogenesis of several diseases such as diabetes mellitus. Diabetes mellitus is a disorder caused by multiple genetic and environmental factors. Examination of Hungarian diabetic and acatalasemic patients showed that an increased frequency of catalase gene mutations exists among diabetes patients. Inherited catalase deficiency may increase the risk of type 2 diabetes mellitus, especially for females. Early onset of type 2 diabetes occurs with inherited catalase deficiency. Low levels of SOD and glutathione peroxidase could contribute to complications caused by increased oxidative stress.

Inherited catalase deficiency: Is it benign or a factor in various age related disorders?

Hydrogen peroxide was - and is still - considered toxic for a wide range of living organisms. Oxidative stress occurs when there is an excess of pro-oxidants over antioxidants and it has been implicated in several diseases. Catalase is involved in hydrogen peroxide catabolism and is important in defense against oxidative stress. Acatalasemia means the inherited near-total deficiency of catalase activity, usually in reference to red cell catalase. Acatalasemia was thought at first to be an asymptotic disorder. In the absence of catalase, neither the Japanese, or Hungarian acatalasemics nor acatalasemic mice had significantly increased blood glutathione peroxidase activity. In animal models, catalase deficient tissues show much slower rates of removal of extracellular hydrogen peroxide. In catalase knock-out mice, a decreased hydrogen peroxide removing capacity and increased reactive oxygen species formation were reported. Hydrogen peroxide may cause methemoglobinemia in patients with catalase deficiency. During anesthesia for a Japanese acatalasemic patient the disinfection with hydrogen peroxide solution caused severe methemoglobinemia. Patients with inherited catalase deficiency, who are treated with uric acid oxidase (rasburicase) may experience very high concentrations of hydrogen peroxide and may suffer from methemoglobinemia and hemolysis. The high (18.5%) prevalence of diabetes mellitus in inherited catalase deficient individuals and the earlier (10 years) manifestation of the disease may be attributed to the oxidative damage of oxidant sensitive, insulin producing pancreatic beta-cells. Ninety-seven of 114 acatalasemics had diseases related to oxidative stress and aging. The oxidative stress due to catalase deficiency could contribute to the manifestation of diabetes while for the other diseases it may be one of the factors in their causations. In summary, inherited catalase deficiency is associated with clinical features, pathologic laboratory test results, age and oxidative stress related disorders. Rather than considering it a benign condition, it should be considered as a complicating condition for aging and oxidative stress.

Effects of rs769217 and rs1001179 polymorphisms of catalase gene on blood catalase, carbohydrate and lipid biomarkers in diabetes mellitus

Abstract Oxidative stress and deficiency of the enzyme catalase, which is the primary scavenger of the oxidant H2O2, may contribute to diabetes. The current study examined two polymorphisms in the catalase gene, −262C>nT in the promoter and 111C>T in exon 9, and their effects on blood catalase activity as well as on concentrations of blood glucose, haemoglobin A1c, triglyceride, cholesterol, HDL, LDL, ApoA-I and ApoB. Subjects were type-1 and type-2 diabetics. We evaluated PCR-single strand conformational polymorphism for 111C>T and PCR-restriction fragment length polymorphism for − 262C>T. TT genotype frequency of 111C>T polymorphism was increased in type-1 diabetes. Type-2 diabetics with the CC or CT genotypes had decreased catalase and increased glucose, hemoglobinA1c and ApoB. Type-2 diabetics who have TT genotype in −262C>T may have elevated risk for diabetes complications; these patients had the lowest mean catalase and HDL, as well as the highest glucose, haemoglobin A1c, cholesterol and ApoB.

Decreased blood catalase activity is not related to specific beta-thalassemia mutations in Hungary.

Introduction:  Thalassemia erythrocytes are exposed to oxidative stress especially to hydrogen peroxide, which is regulated with the enzyme catalase. The aim of this study was to examine blood catalase activity and the relationship of blood catalase and beta‐thalassemia gene mutations.

A simple method for examination of polymorphisms of catalase exon 9: rs769217 in Hungarian microcytic anemia and beta-thalassemia patients.

Catalase decreases the high, toxic concentrations of hydrogen peroxide but it lets the physiological, low concentrations in the cells mainly for signaling purposes. Its decreased activity may contribute to development of several pathological conditions. Catalase mutations occur frequently in exon 9, these were examined with different, complicated and costly methods. The aim of the current study was to evaluate a method for screening of polymorphisms in catalase exon 9. We used the slab gel electrophoresis of PCR amplicons without denaturation and silver staining for visualization of the DNA bands. We detected extra DNA bands in the 400-800 bp region of the catalase exon 9. Their single stranded nature was proved with nucleotide sequence analyses, comparison with the standard SSCP, staining with Sybr Green II and Sybr Green I, ethidium bromide, no digestion with RFLP (BstX I), and digestion with plant nuclease. We used this method for examination of polymorphisms of catalase exon 9 in microcytic anemia and beta-thalassemia patients. The lowest blood catalase activities were detected in microcytic anemia and beta-thalassemia patients with the TT genotypes of the C111T polymorphism. This method was sensitive for detection of G113A acatalasemia mutation, but poorly detected C37T and G5A acatalasemia mutations.

Further acatalasemia mutations in human patients from Hungary with diabetes and microcytic anemia.

In blood, the hydrogen peroxide concentration is regulated by catalase. Decreased activity of catalase may lead to increased hydrogen peroxide concentration, which may contribute to the manifestation of age-related disease. The aim of this study is to examine association of decreased blood catalase activity and catalase exon mutations in patients (n=617) with diabetes (n=380), microcytic anemia (n=58), beta-thalassemia (n=43) and presbycusis (n=136) and in controls (n=295). Overall, 51 patients (8.3%) had less than half of normal blood catalase activity. Their genomic DNA was used for mutation screening of all exons and exon/intron boundaries with polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and PCR-heteroduplex analyses, and mutations were verified with nucleotide sequencing. Seven patients (type 2 diabetes (n=3), gestational diabetes (n=1), microcytic anemia (n=2)) had four novel catalase exon mutations namely, c.106_107insC, p.G36Afs*5(n=3, Hungarian type G1), c.379C>T, p.R127Y (n=2, Hungarian type H1), c.390T>C, p.R129L, (n=1, Hungarian type H2) and c.431A>T, p.N143V (n=1, Hungarian type H3). In patients with decreased blood catalase, the incidence of acatalasemia mutations was significantly high (P<0.0002) in microcytic anemia, type 2 and gestational diabetes. The four novel mutations were probably responsible for low blood catalase activity in 7/51 patients. In the remainder of the cases, other polymorphisms and epigenetic/regulatory factors may be involved.

Acatalasemia and type 2 diabetes mellitus

The catalase enzyme decomposes the toxic concentrations of hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly reactive small molecule and its excessive concentration may cause significant damages to proteins, deoxyribonucleic acid, ribonucleic acid and lipids. Acatalasemia refers to inherited deficiency of the catalase enzyme. In this review the authors discuss the possible role of the human catalase enzyme, the metabolism of hydrogen peroxide, and the phenomenon of hydrogen peroxide paradox. In addition, they review data obtained from Hungarian acatalasemic patients indicating an increased frequency of type 2 diabetes mellitus, especially in female patients, and an early onset of type 2 diabetes in these patients. There are 10 catalase gene variants which appear to be responsible for decreased blood catalase activity in acatalasemic patients with type 2 diabetes. It is assumed that low levels of blood catalase may cause an increased concentration of hydrogen peroxide which may contribute to the pathogenesis of type 2 diabetes mellitus.

Blood Catalase Activities, Catalase Gene Polymorphisms and Acatalasemia Mutations in Hungarian Patients with Diabetes Mellitus

Introduction: Catalase decomposes hydrogen peroxide into oxygen and water. Its low concentration could be involved in signaling while its high concentration is toxic.

A veleszületett katalázhiány (acatalasaemia) és a 2-es típusú diabetes mellitus@@@Acatalasemia and type 2 diabetes mellitus

The catalase enzyme decomposes the toxic concentrations of hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly reactive small molecule and its excessive concentration may cause significant damages to proteins, deoxyribonucleic acid, ribonucleic acid and lipids. Acatalasemia refers to inherited deficiency of the catalase enzyme. In this review the authors discuss the possible role of the human catalase enzyme, the metabolism of hydrogen peroxide, and the phenomenon of hydrogen peroxide paradox. In addition, they review data obtained from Hungarian acatalasemic patients indicating an increased frequency of type 2 diabetes mellitus, especially in female patients, and an early onset of type 2 diabetes in these patients. There are 10 catalase gene variants which appear to be responsible for decreased blood catalase activity in acatalasemic patients with type 2 diabetes. It is assumed that low levels of blood catalase may cause an increased concentration of hydrogen peroxide which may contribute to the pathogenesis of type 2 diabetes mellitus.

A veleszületett katalázhiány (acatalasaemia) és a 2-es típusú diabetes mellitus

The catalase enzyme decomposes the toxic concentrations of hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly reactive small molecule and its excessive concentration may cause significant damages to proteins, deoxyribonucleic acid, ribonucleic acid and lipids. Acatalasemia refers to inherited deficiency of the catalase enzyme. In this review the authors discuss the possible role of the human catalase enzyme, the metabolism of hydrogen peroxide, and the phenomenon of hydrogen peroxide paradox. In addition, they review data obtained from Hungarian acatalasemic patients indicating an increased frequency of type 2 diabetes mellitus, especially in female patients, and an early onset of type 2 diabetes in these patients. There are 10 catalase gene variants which appear to be responsible for decreased blood catalase activity in acatalasemic patients with type 2 diabetes. It is assumed that low levels of blood catalase may cause an increased concentration of hydrogen peroxide which may contribute to the pathogenesis of type 2 diabetes mellitus.